Haptic Feedback System for a Virtual Environment ECE 4901 | Team - - PowerPoint PPT Presentation

Haptic Feedback System for a Virtual Environment

ECE 4901 | Team 1820 | Fall 2017

Project Sponsor: Professor Steven Harrison - University of Connecticut Psychology Department

Team 1820:

Derrick Chen (CompE), Benjamin Marcotte (EE) Ethan Freund (EE), Meridith Kuperstein (CSE/EE)

Advisor:

Professor Shengli Zhou

Overview

• Project Overview and Background
• Project Requirements
• Chosen Implementation
• Materials and Techniques Used
• Simulating Physics and Programming
• Current Status
• Future Plans

Haptic Feedback Systems

“...Of or relating to tactile sensations and the sense of touch as a method of interacting with computers and electronic devices: smartphones that incorporate haptic feedback [1].”

[1] http://www.dictionary.com/browse/haptic

The Project

• Professor Steven Harrison studies human-object interaction, and wants a 1D

linear motion haptic feedback system

• The linear motion system will allow users to simulate frictional forces, and other

forces, while pushing a real physical blocks in one dimension and will interact with virtual environments, which they can see projected on a screen

• This system will be used to study how people interact and adapt their motion in

novel, simulated environments with touch feedback

Linear Haptic Feedback System

Virtual Environment Projection Force Feedback Will be able to simulate interactions with springs, different surface coefficients of friction, and virtual walls.

Requirements

• Must handle loads up to 150N
• Feedback delay must be <10ms, or small enough that delay is

unnoticeable

• Must have minimal audible noise
• Must have built in safety features
• Must have two blocks that can move either independently of

each other or concurrently

Implementation

Belt-Driven Motor Braking System

Motor Force Sensor Motor Controller Circuit CPU Sliding Block F_applied (hand) F_applied (motor) Applied motor torque DAQ Encoder

Implementation Cons

• Delay could be a problem

○ Delays come from I/O interface, computer processing, and motor operation

• High cost motors

○ Based on torque and control requirements ○ Currently looking at a $2,000 motor system

• Initial friction may be high

○ Friction comes from wheel bearings on cart, wheel to rail friction, internal motor resistance, and pulley friction

• Sound from metal wheels on a metal rail

Materials Used

Data Acquisition:

• National Instruments USB-6255 DAQ

○ 80 analog input & 2 analog output channels ■ ±5V or ±10V outputs ○ Up to 1.25 MS/s ○ 16-bit analog resolution

Computer:

• Digital Storm

○ Enough processing power for incoming DAQ data ○ USB 3.0 ○ Also, handles display graphics

Force Sensor:

• ATI 9105-TW-MINI-58

○ Measures force/torque on XYZ axis ○ Handles a lot of force ■ 21000N or 4721 lbs on XY axis ■ 48000N or 10791 lbs on Z axis ○ Small and compact ■ 58mm wide & 30mm tall

Potential Materials - Motors

Brushless Servo Motors

• Offer high acceleration/deceleration
• Used in precision applications

○ Precise control of position & velocity

• Produce little noise

Options:

• Kollmorgen Motor

○ Ethernet or analog control ○ Good torque feedback

• StepServo

○ Ethernet or analog control ○ Clicks on rotation

• ClearPath Teknic

○ Runs on digital frequency/PWM signal ○ Good torque feedback from specifications ■ No access for a sample

Potential Materials - Rails

V Slot Rails

• Has only one method of implementation

○ Acts as a linear rail ○ Uses a specific wheel

• Cheap & modular
• Smooth movement along a rail with a cart

T Slot Rails

• Requires additional bearings to be a

linear rail

• Many different implementations are

possible

Where We Currently Are

• Built Prototype
• Testing different types of motors for ease of use and ‘smoothness’
• Comparing different rail systems for cost and modularity
• After testing, decide on final configuration

System Modeling in Virtual Space

Simulated Force (Friction or Spring)

Normal Force Horizontal User Input Force Weight and Downward User Force Simulated Force Equations Spring System: Fspring= -k*x Friction: When Input Force > μ฀N, Ffriction= -μkN When Input Force < μ฀N, Ffriction=-Input Force

Programming

• Language

○ C++, possibly some Python ○ Compatibility with hardware

• 3D Environment

○ Visually simulates real world physics ○ Obstacles and force fields

• Currently in pseudo-code phase

○

Initial testing will be simplified and from a sample data set

Cost Projection

Item Cost ($) Test budget 200 Rail Mount System 200-300 Motor System 1500-2500 Computing System 0 (Readily Available) Force Sensors 0 (Readily Available) Data Acquisition System 0 (Readily Available) Total 1900-3000

Future Plans

End of Fall 2017 Semester- Make final hardware decision and

• rder parts

January 2018- Start the physical build Mid February 2018- Finish first build Mid February 2018- March 2018- Test and redesign End of March 2018- Finish final product

Questions?